The overall goal of our research is to introduce into a new context, the primary care pediatric office, a parent training program designed to improve parenting skills and diminish behavioral symptoms in very young children at risk for diagnoses of Attention Deficit/Hyperactivity Disorder (ADHD) and Oppositional Defiant Disorder (ODD). This application describes a multi-site randomized controlled trial in eight diverse pediatric practices of the Incredible Years parent training program, which has been well-validated and shown to be efficacious in multiple settings. As a result of a pilot study in two pediatric practice settings, funded through an R-21 grant from the NIMH, we have a) developed and standardized necessary materials;b) demonstrated the project's feasibility;c) determined preliminary effect sizes;d) improved the protocol for use in pediatric settings;and e) secured agreements from diverse pediatric practices to participate in the project. Pediatricians will institute a systematic procedure for administering a brief screening questionnaire to parents prior to their child's 2- and 3-year well child visits. Parents who report elevated symptoms of hyperactivity, impulsivity, aggression, oppositionality, and inattention will be invited to join the project. If they agree they will be randomly assigned to participate in either the experimental (immediate) parent training group or the waitlist control condition (parent training group after 12 month delay). The parent training groups will be co- led by a nurse practitioner who is part of the research staff and a member of the pediatric office staff after appropriate training. In order to measure outcomes and to establish moderators of the efficacy of this intervention program in this setting, we will assess a) severity of primary symptoms;b) functional status/impairment;c) environmental context;d) consumer satisfaction;and e) service use/costs. Participants in both conditions will be followed for a minimum of 2 years after the parent training group with periodic assessments.